Conventionally, a fishing spinning reel includes a rotor rotationally driven by rotational handle operation and a spool reciprocated back and forth and around which a fishing line is wound. As generally known, the rotor meshes with a drive gear mounted on a handle shaft and is fixed with a rotor nut on the front end of a pinion gear supported so as to be rotatable in a direction orthogonal to the handle shaft, such that the rotor is rotationally driven. The spool shaft supporting the spool is inserted through the pinion gear and reciprocated back and forth by an oscillation device (reciprocation device) driven by the drive gear.
Accordingly, upon rotational operation of the handle, the spool shaft, which is inserted through the pinion gear, is reciprocated in the pinion gear rotationally driven. When a large load is imparted on the spool to bend the spool shaft, a larger contact pressure between the inner surface of the pinion gear and the spool shaft is produced to increase a sliding resistance on the spool shaft and degrade the smoothness of the rotational operation of the handle.
To overcome this problem, Japanese Utility Model Application Publication No. Hei 6-11469 (the “'469 Publication”) for example discloses that rolling members are interposed between the inner circumferential surface of the pinion gear and the outer circumferential surface of the spool shaft to support the spool shaft on the inner circumferential surface of the pinion gear via rolling guide.
It is disclosed in Japanese Patent Application Publication No. 2001-258438 (the “'438 Publication”) that a recess is formed along the axial direction in the inner surface of the pinion gear to form a gap between the inner surface of the pinion gear and the outer surface of the spool shaft, thereby reducing the sliding resistance on the spool shaft.
The '438 Publication also discloses that a rotor nut is screwed on the front portion of the pinion gear, the spool shaft is supported at its front end by a bearing provided between the rotor nut and the spool shaft, and the spool shaft is also supported at its rear end by a bearing provided on the rear portion of the pinion gear, thereby to separate the inner circumferential surface of the pinion gear from the outer circumferential surface of the spool shaft.
However, the support structure of the spool shaft disclosed in the '469 Publication, which employs rolling guide by the rolling members interposed between the inner circumferential surface of the pinion gear and the outer circumferential surface of the spool shaft, requires hardness and durability of the pinion gear and the spool shaft and thus limits the applicable materials and the degree of freedom of design. Such a support structure also requires space for rolling guide reciprocating back and forth and thus limits the size and shape.
In both the '438 Publication and Japanese Patent Application Publication No. 2006-333705 (the “'705 Publication”), the distance between the two support points at which the spool shaft is supported is small (in the '438 Publication, the two support points are within the axial length of the pinion gear; and in the 705 Publication, the two support points are near the opposite end surfaces of the pinion gear). Thus, due to the small gap between the inner circumferential surface of the pinion gear and the outer circumferential surface of the spool shaft, the spool shaft is prone to rattle in radial directions.
If a bearing is disposed between the rotor nut screwed on the pinion gear and the spool shaft, it is difficult to achieve the concentricity of the rotor nut with respect to the pinion gear (accordingly, it is difficult to achieve the concentricity of the spool shaft with respect to the pinion gear). Therefore, when the pinion gear is rotated, the spool shaft may be rotated eccentrically. Further, since a slide member of an oscillation device is positioned in accordance with positioning of the spool shaft, the spool shaft (spool) may not be reciprocated back and forth accurately if the spool rattles or rotates eccentrically.